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285 lines
9.0 KiB
285 lines
9.0 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* linux/include/linux/clocksource.h |
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* |
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* This file contains the structure definitions for clocksources. |
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* |
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* If you are not a clocksource, or timekeeping code, you should |
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* not be including this file! |
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*/ |
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#ifndef _LINUX_CLOCKSOURCE_H |
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#define _LINUX_CLOCKSOURCE_H |
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#include <linux/types.h> |
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#include <linux/timex.h> |
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#include <linux/time.h> |
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#include <linux/list.h> |
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#include <linux/cache.h> |
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#include <linux/timer.h> |
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#include <linux/init.h> |
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#include <linux/of.h> |
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#include <asm/div64.h> |
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#include <asm/io.h> |
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struct clocksource; |
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struct module; |
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#if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \ |
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defined(CONFIG_GENERIC_GETTIMEOFDAY) |
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#include <asm/clocksource.h> |
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#endif |
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#include <vdso/clocksource.h> |
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/** |
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* struct clocksource - hardware abstraction for a free running counter |
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* Provides mostly state-free accessors to the underlying hardware. |
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* This is the structure used for system time. |
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* |
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* @read: Returns a cycle value, passes clocksource as argument |
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* @mask: Bitmask for two's complement |
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* subtraction of non 64 bit counters |
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* @mult: Cycle to nanosecond multiplier |
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* @shift: Cycle to nanosecond divisor (power of two) |
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* @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs) |
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* @maxadj: Maximum adjustment value to mult (~11%) |
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* @archdata: Optional arch-specific data |
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* @max_cycles: Maximum safe cycle value which won't overflow on |
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* multiplication |
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* @name: Pointer to clocksource name |
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* @list: List head for registration (internal) |
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* @rating: Rating value for selection (higher is better) |
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* To avoid rating inflation the following |
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* list should give you a guide as to how |
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* to assign your clocksource a rating |
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* 1-99: Unfit for real use |
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* Only available for bootup and testing purposes. |
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* 100-199: Base level usability. |
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* Functional for real use, but not desired. |
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* 200-299: Good. |
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* A correct and usable clocksource. |
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* 300-399: Desired. |
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* A reasonably fast and accurate clocksource. |
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* 400-499: Perfect |
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* The ideal clocksource. A must-use where |
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* available. |
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* @flags: Flags describing special properties |
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* @enable: Optional function to enable the clocksource |
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* @disable: Optional function to disable the clocksource |
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* @suspend: Optional suspend function for the clocksource |
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* @resume: Optional resume function for the clocksource |
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* @mark_unstable: Optional function to inform the clocksource driver that |
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* the watchdog marked the clocksource unstable |
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* @tick_stable: Optional function called periodically from the watchdog |
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* code to provide stable syncrhonization points |
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* @wd_list: List head to enqueue into the watchdog list (internal) |
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* @cs_last: Last clocksource value for clocksource watchdog |
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* @wd_last: Last watchdog value corresponding to @cs_last |
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* @owner: Module reference, must be set by clocksource in modules |
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* |
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* Note: This struct is not used in hotpathes of the timekeeping code |
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* because the timekeeper caches the hot path fields in its own data |
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* structure, so no cache line alignment is required, |
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* |
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* The pointer to the clocksource itself is handed to the read |
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* callback. If you need extra information there you can wrap struct |
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* clocksource into your own struct. Depending on the amount of |
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* information you need you should consider to cache line align that |
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* structure. |
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*/ |
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struct clocksource { |
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u64 (*read)(struct clocksource *cs); |
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u64 mask; |
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u32 mult; |
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u32 shift; |
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u64 max_idle_ns; |
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u32 maxadj; |
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#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
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struct arch_clocksource_data archdata; |
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#endif |
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u64 max_cycles; |
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const char *name; |
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struct list_head list; |
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int rating; |
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enum vdso_clock_mode vdso_clock_mode; |
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unsigned long flags; |
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int (*enable)(struct clocksource *cs); |
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void (*disable)(struct clocksource *cs); |
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void (*suspend)(struct clocksource *cs); |
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void (*resume)(struct clocksource *cs); |
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void (*mark_unstable)(struct clocksource *cs); |
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void (*tick_stable)(struct clocksource *cs); |
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/* private: */ |
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#ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
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/* Watchdog related data, used by the framework */ |
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struct list_head wd_list; |
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u64 cs_last; |
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u64 wd_last; |
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#endif |
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struct module *owner; |
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}; |
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/* |
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* Clock source flags bits:: |
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*/ |
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#define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
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#define CLOCK_SOURCE_MUST_VERIFY 0x02 |
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#define CLOCK_SOURCE_WATCHDOG 0x10 |
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#define CLOCK_SOURCE_VALID_FOR_HRES 0x20 |
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#define CLOCK_SOURCE_UNSTABLE 0x40 |
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#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 |
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#define CLOCK_SOURCE_RESELECT 0x100 |
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/* simplify initialization of mask field */ |
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#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0) |
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static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) |
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{ |
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/* freq = cyc/from |
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* mult/2^shift = ns/cyc |
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* mult = ns/cyc * 2^shift |
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* mult = from/freq * 2^shift |
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* mult = from * 2^shift / freq |
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* mult = (from<<shift) / freq |
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*/ |
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u64 tmp = ((u64)from) << shift_constant; |
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tmp += freq/2; /* round for do_div */ |
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do_div(tmp, freq); |
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return (u32)tmp; |
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} |
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/** |
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* clocksource_khz2mult - calculates mult from khz and shift |
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* @khz: Clocksource frequency in KHz |
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* @shift_constant: Clocksource shift factor |
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* |
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* Helper functions that converts a khz counter frequency to a timsource |
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* multiplier, given the clocksource shift value |
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*/ |
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static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) |
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{ |
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return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC); |
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} |
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/** |
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* clocksource_hz2mult - calculates mult from hz and shift |
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* @hz: Clocksource frequency in Hz |
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* @shift_constant: Clocksource shift factor |
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* |
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* Helper functions that converts a hz counter |
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* frequency to a timsource multiplier, given the |
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* clocksource shift value |
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*/ |
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static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) |
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{ |
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return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC); |
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} |
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/** |
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* clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
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* @cycles: cycles |
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* @mult: cycle to nanosecond multiplier |
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* @shift: cycle to nanosecond divisor (power of two) |
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* |
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* Converts clocksource cycles to nanoseconds, using the given @mult and @shift. |
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* The code is optimized for performance and is not intended to work |
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* with absolute clocksource cycles (as those will easily overflow), |
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* but is only intended to be used with relative (delta) clocksource cycles. |
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* |
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* XXX - This could use some mult_lxl_ll() asm optimization |
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*/ |
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static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) |
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{ |
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return ((u64) cycles * mult) >> shift; |
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} |
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extern int clocksource_unregister(struct clocksource*); |
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extern void clocksource_touch_watchdog(void); |
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extern void clocksource_change_rating(struct clocksource *cs, int rating); |
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extern void clocksource_suspend(void); |
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extern void clocksource_resume(void); |
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extern struct clocksource * __init clocksource_default_clock(void); |
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extern void clocksource_mark_unstable(struct clocksource *cs); |
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extern void |
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clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles); |
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extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now); |
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extern u64 |
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clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); |
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extern void |
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clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); |
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/* |
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* Don't call __clocksource_register_scale directly, use |
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* clocksource_register_hz/khz |
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*/ |
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extern int |
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__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); |
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extern void |
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__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); |
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/* |
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* Don't call this unless you are a default clocksource |
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* (AKA: jiffies) and absolutely have to. |
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*/ |
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static inline int __clocksource_register(struct clocksource *cs) |
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{ |
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return __clocksource_register_scale(cs, 1, 0); |
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} |
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static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) |
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{ |
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return __clocksource_register_scale(cs, 1, hz); |
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} |
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static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) |
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{ |
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return __clocksource_register_scale(cs, 1000, khz); |
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} |
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static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) |
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{ |
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__clocksource_update_freq_scale(cs, 1, hz); |
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} |
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static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) |
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{ |
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__clocksource_update_freq_scale(cs, 1000, khz); |
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} |
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#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT |
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extern void clocksource_arch_init(struct clocksource *cs); |
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#else |
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static inline void clocksource_arch_init(struct clocksource *cs) { } |
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#endif |
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extern int timekeeping_notify(struct clocksource *clock); |
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extern u64 clocksource_mmio_readl_up(struct clocksource *); |
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extern u64 clocksource_mmio_readl_down(struct clocksource *); |
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extern u64 clocksource_mmio_readw_up(struct clocksource *); |
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extern u64 clocksource_mmio_readw_down(struct clocksource *); |
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extern int clocksource_mmio_init(void __iomem *, const char *, |
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unsigned long, int, unsigned, u64 (*)(struct clocksource *)); |
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extern int clocksource_i8253_init(void); |
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#define TIMER_OF_DECLARE(name, compat, fn) \ |
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OF_DECLARE_1_RET(timer, name, compat, fn) |
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#ifdef CONFIG_TIMER_PROBE |
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extern void timer_probe(void); |
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#else |
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static inline void timer_probe(void) {} |
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#endif |
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#define TIMER_ACPI_DECLARE(name, table_id, fn) \ |
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ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn) |
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#endif /* _LINUX_CLOCKSOURCE_H */
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